> From: Michael Lovejoy [mailto:michael@palaeoproductions.fsnet.co.uk]
>
> Did anyone catch the Keratinous covered dinosaur skulls thing by Horner /
> Marshall at the SVP? If you did, could you briefly outline what it was
> about?
>
In brief:
Horner pointed out that the main evidence for keratinous sheaths on the
horns and beaks of ceratopsids is the pattern of blood vessels found
imprinted on the underlying bone. However, he demonstrated that precisely
the same pattern of blood vessels is found broadly expressed over the dorsal
surface of the frills, along the facial bones, and much of the skull in
general. Therefore, he suggested that it was a kind of double standard to
use these marks as evidence of keratinous sheaths for some areas but not for
the others.
An interesting hypothesis, and one which at first glance is difficult to
reject. What would be most informative is knowledge from modern dissections
and the like to establish if the blood vessel pattern is indeed only
associated with keratin, or if it might underly other integumentary tissues.
Hope that helps!
Thomas R. Holtz, Jr.
Vertebrate Paleontologist
Department of Geology Director, Earth, Life & Time Program
University of Maryland College Park Scholars
College Park, MD 20742
http://www.geol.umd.edu/~tholtz/tholtz.htmhttp://www.geol.umd.edu/~jmerck/eltsite
Phone: 301-405-4084 Email: tholtz@geol.umd.edu
Fax (Geol): 301-314-9661 Fax (CPS-ELT): 301-405-0796